The overall objective of this proposal is an investigation of the oxidative metabolism of the neutrophil with particular emphasis on the relationship of this activity during phagocytosis. The following specific aims are directed toward this goal: 1. To develop sensitive isotopic and fluorometric assays to measure NADH and NADPH oxidase activities. 2. To characterize and compare the two oxidase activities in normal human polymorphonuclear leukocytes. 3. To investigate the activities of both enzymes in the granule fractions of PMNL obtained from patients with chronic granulomatous disease. 4. To attempt to delineate the mechanism of activation of NADPH (and possibly NADH) oxidase by phagocytosis. 5. To identify the subcellular localization of the oxidase enzyme(s) within the cell. 6. Initiate attempts to purify the enzyme(s) in an effort to detemine whether the cell possesses two separate oxidases or a single oxidase which can utilize either NADH or NADPH as substrate. BIBLIOGRAPHIC REFERENCES: DeChatelet, L.R.: Oxidative bactericidal of polymorphonuclear leukocytes. J. Inf. Dis. 131:295 (1975). DeChatelet, L.R., McPhail, L.C., Mullikin, D., And McCall, C.E.: An isotopic assay for NADPH oxidase activity and some characteristics of the enzyme from human polymorphonuclear leukocytes. J. Clin. Invest. 55:714 (1975).